The invention relates to an incremental longitudinal measuring instrument for the measuring or adjusting of a relative position of two ojects, wherein a measuring scale and a displaceable sensor housing unit are enclosed in an elongated hollow body resistant to bending to screen the measuring scale and the sensor unit from environmental influences. In particular, the present invention relates to a longitudinal measuring instrument in which the hollow body is fastened to one of the two objects to be measured by means of joints with curved surfaces.
The mounting surfaces for the type of measuring instruments to which the present invention is directed are typically on machine tools and other such devices. Such mounting surfaces are generally not level. In the prior art apparatus are known in which the hollow body of a longitudinal measuring instrument is fastened to a machine tool mounting surface by non-jointed fastening means, such as the unarticulated L-shaped brackets disclosed in May et al U.S. Pat. No. 3,815,125, Weig U.S. Pat. No. 3,816,002, and Litke U.S. Pat. No. 3,816,003. These prior art fastening means typically cause deformation of the measuring instrument and its graduation scale when the instrument is mounted to an uneven machine tool mounting surface, thereby adversely affecting the instrument's precision. Releveling and reworking of the mounting surfaces to correct this effect is generally quite time consuming and expensive.